Year	Percent
1990	15.3
1991	15.011
1992	14.726
1993	14.446
1994	14.17
1995	14.297
1996	14.546
1997	14.62
1998	14.782
1999	15.076
2000	15.266
2001	15.202
2002	15.168
2003	14.938
2004	14.813
2005	14.824
2006	14.852
2007	14.817
2008	14.552
2009	14.163
2010	14.051
2011	14.123
2012	14.312
2013	14.386
2014	14.503
2015	14.64
2016	14.925
2017	14.856
2018	14.788
2019	14.72
2020	14.652
2021	14.583
2022	14.515
2023	14.447
2024	14.379
2025	14.311
2026	14.242
2027	14.174
2028	14.106
2029	14.038
2030	13.969